Shoelaces, sometimes called shoestrings (US English) or bootlaces (UK English), are a system commonly used to secure shoes, boots and other footwear. They typically consist of a pair of strings or cords, one for each shoe, finished off at both ends with stiff sections, known as aglets. Each shoelace typically passes through a series of holes, eyelets, loops or hooks on either side of the shoe. Loosening the lacing allows the shoe to open wide enough for the foot to be inserted or removed. Tightening the lacing and tying off the ends secures the foot within the shoe. Traditional shoelaces were made of leather, cotton, jute, hemp, or other materials used in the manufacture of rope. Modern shoelaces often incorporate various synthetic fibers, which are generally more slippery and thus more prone to coming undone than those made from traditional fibers, although synthetic shoelaces tend to suffer less wear from friction and are less susceptible to rotting from moisture.